Method and apparatus for processing a composite signal including a desired spread spectrum signal and an undesired narrower-band interfering signal

An apparatus for processing a composite signal including a desired spread spectrum signal and an undesired narrow-band interfering signal having a center frequency, the apparatus comprising:

• a frequency-detector for determining a frequency of the interfering signal;
• a first shifter coupled to the frequencydetector and coupled to the composite signal for shifting the frequency of the composite signal from a first frequency range, the frequency shifter shifting the composite signal by an amount determined from the frequency of the interfering signal, thereby creating a shifted composite signal in which the interfering signal is at a predetermined frequency;
• a filter coupled to the first shifter for attenuating signals near the predetermined frequency, the filter to filter out the shifted composite signal to remove the interfering signal and thus provide an interference-attenuated shifted signal;
• and
• a second shifter coupled to the frequency detector and the filter, the second shifter for shifting the interference-attenuated shifted signal by said amount determined from the frequency of the interfering signal, thereby returning the desired spread spectrum signal to the first frequency range.

A wireless communication device receiving and processing a composite signal including a desired spread spectrum signal and an undesired interfering signal having a narrower band width than the spread spectrum signal, the receiver comprising:

• an antenna for receiving a signal;
• receiver front-end circuitry coupled to the antenna and down-converting the received signal to the composite signal;
• an analog-to-digital converter for converting the output of the receiver front end circuitry to a digital signal;
• and
• a circuit for removing the undesired interference signal coupled to the receiver front end, the circuit comprising:
• a frequency detector to determine a characteristic frequency of the interfering signal;
• a first shifter coupled to the frequency detector and coupled to the composite signal for shifting the composite signal by an amount corresponding to the characteristic frequency of the interfering signal, thereby creating a shifted composite signal in which the frequency of the interfering signal is at a predetermined value;
• a filter coupled to the first shifter for filtering the shifted composite signal to remove the interfering signal and outputting a filtered composite signal with the interfering signal attenuated;
• and
• a second shifter coupled to the frequency detector and coupled to the filter for shifting the filtered composite signal in frequency by said amount corresponding to the characteristic frequency of the interfering signal, thereby returning the desired spread spectrum signal to the frequency range prior to filtering in the first filter;
• and
• backend circuitry coupled to the output of the second shifter for further processing the desired spread spectrum signal.